internal: minicore: add the Hash derive macro to the prelude

This commit adds the core::hash::Hash derive macro to the prelude, just like rustc does. They define
the macro in a private core::hash::macros module, presumably to differentiate between the macro and
trait (who otherwise share the same path). Only the macro is in the prelude, which minicore now mirrors.

I've also added support for multiple "line regions" in minicore, as the prelude re-export needs both
"hash" and "derive". The syntax looks as follows: "// :hash, derive".

Author: IvarWithoutBones

crates/test-utils/src/fixture.rs

@@ -427,10 +427,12 @@ impl MiniCore {
                 continue;
             }
 
-            let mut line_region = false;
+            let mut line_regions = 0;
             if let Some(idx) = trimmed.find("// :") {
-                line_region = true;
-                active_regions.push(&trimmed[idx + "// :".len()..]);
+                for region in trimmed[idx + "// :".len()..].split(", ") {
+                    active_regions.push(region);
+                    line_regions += 1;
+                }
             }
 
             let mut keep = true;
@@ -444,9 +446,8 @@ impl MiniCore {
             if keep {
                 buf.push_str(line);
             }
-            if line_region {
-                active_regions.pop().unwrap();
-            }
+
+            active_regions.truncate(active_regions.len() - line_regions);
         }
 
         if !active_regions.is_empty() {

crates/test-utils/src/minicore.rs

@@ -199,8 +199,12 @@ pub mod hash {
     }
 
     // region:derive
-    #[rustc_builtin_macro]
-    pub macro Hash($item:item) {}
+    pub(crate) mod macros {
+        #[rustc_builtin_macro]
+        pub macro Hash($item:item) {}
+    }
+
+    pub use macros::Hash;
     // endregion:derive
 }
 // endregion:hash
@@ -1678,6 +1682,7 @@ pub mod prelude {
             convert::AsRef,                          // :as_ref
             convert::{From, Into},                   // :from
             default::Default,                        // :default
+            hash::macros::Hash,                      // :hash, derive
             iter::{IntoIterator, Iterator},          // :iterator
             macros::builtin::{derive, derive_const}, // :derive
             marker::Copy,                            // :copy